Blood, Lymph and Immunity

Question 1

What is the direction of lymph flow?

Answer 1

1. afferent lymphatics
2. subcapsular sinus
3. efferent lymphatics

Question 2

What cells are found in lymph nodes?

Answer 2

• lymphocytes
• phagocytes

Question 3

What are the tissues of the macrophage and mononuclear cells phagocytic “system”?

Answer 3

• lymph nodes
• tissue macrophages
• hepatic endothelium
• splenic endothelium
• bone marrow sinusoids
• mucosa-associated lymphatic tissue (MALT)
• gut-associated lymphatic tissue (GALT)
• tonsils (pharynx)
• Peyer’s patches
• lymphatic drainage
  
  • thoracic duct
  • fluid returns back to the general circulation
  • drains lymph and chyle back to near the cranial vena cava

Question 4

What are the palpable lymph nodes?

Answer 4

palpable lymph nodes – parotid (dog), mandibular, superficial cervical, axillary, superficial inguinal, popliteal

Question 5

What is the spleen?

Answer 5

• a reservoir for red blood cells
• a sight of immune surveillance (especially phagocytosis) and removal of aged or damaged RBCs

Question 6

What is the thymus?

Answer 6

• disappears (atrophies) in the adult after puberty
• cortex – site of T lymphocyte production, which go out and populate lymphoid tissues and structures

Question 7

What is the 3 functions of blood?

Answer 7

1. transport of gases, nutrients, metabolic waste products, cells and hormones
2. regulation of body temperature and acid:base balance (pH)
3. immunological defense

Question 8

Describe blood volume among species…

Answer 8

• n liters as % of body weight (kilograms) – important to consider to recognize in cases of fluid loss and circulation for pharmacology 2.2 lbs = 1 kg
• human – 7% of body weight
• dog – 7.2%
• cow – 7.7%
• sheep – 8%
• horse – 9.7%

Question 9

What are the components of blood?

Answer 9

• fluid = plasma
  
  • constant exchange of inorganic salts with extracellular fluid space
  • contains 3 types of proteins (“plasma proteins”) – the plasma proteins contribute to the colloidal osmotic pressure within the vascular system
  • albumins – most abundant – transport of insoluble substances such as fatty acids
  • globulins – alpha, beta, gamma
    
    • transport proteins
    • gamma = immunoglobulins
  • fibrinogen – blood clotting

Question 10

What is plasma?

Answer 10

serum and clotting factors

Question 11

What is serum?

Answer 11

fluid component after clot is formed

Question 12

Describe red blood cells…

Answer 12

• red blood cells make up 99.9% of blood’s formed elements
  
  • function: the transport of respiratory gasses (O2 and CO2)
  • live about 120 days
  • low RBC count = anemia
  • increased RBC count = polycythemia

Question 13

Describe white blood cells…

Answer 13

• white blood cells – leukocytes
• immunologic functions
  
  • remove and defend against pathogens
  • remove abnormal cells
• observe on peripheral blood smears
• granulocytes or PMNs (polymorphonuclear leukocytes)
  
  • neutrophil
  • eosinophil
  • basophil
• mononuclear cells
  
  • monocytes
  • lymphocytes

Question 14

What is a neutrophil?

Answer 14

• description
  
  • granules contain lysosomal enzymes and bacterial compounds (hydrogen peroxide and superoxide)
  • very dense, segmented nucleus that forms 2-5 lobes –> also called PMNs
• function: 1st line of defense (quick response)
  
  • phagocytosis of small pathogenic microorganisms
  • hydrogen peroxide kills bacteria
• life space : hours - 3 days

Question 15

What is a eosinophil?

Answer 15

• description
  
  • large granules stain red with eosin
  • a bilobed nucleus
• functions
  
  • attack objects (bacteria, protozoa, or cellular debris) by phagocytosis and exocytosis of toxic compound (nitric oxide and cytotoxic enzymes)
  • defend against large multicellular parasites
  • release anti-inflammatory substances in allergic reactions
• life span: 10 - 12 days

Question 16

What is a basophil?

Answer 16

• description
  
  • rare and smaller
  • dense granules stain deep purple or blue with basic dye
  • nucleus generally can not be seen
• functions
  
  • enhance inflammatory response by:
    
    • release histamine
      
      • dilates blood vessels
    • release heparin
      
      • prevents blood clotting
    • tissue mast cells release same compounds, but they are distinct populations with separate origins
• life span: hours - 3 days

Question 17

What is a monocyte?

Answer 17

• description
  
  • largest (twice the diameter of a RBC)
  • spherical
  • nucleus is large and tends to be oval or kidney bean shaped
• functions
  
  • enter peripheral tissues to become a tissue macrophage – major and aggressive phagocytes
  • release chemicals to attract and stimulate other phagocytic cells
  • secrete substances that lure fibroblasts into the region to produce scar tissue
• life span: months

Question 18

What is a lymphocyte?

Answer 18

• description
  
  • slightly larger than RBC
  • round and large nucleus, often look like nuclei without cytoplasm
  • migrate in and out of blood
  • mostly in connective tissues and lymphatic organs
• type and functions
  
  • T cells: cell-mediated immunity: provide “killer” cells to directly attack foreign invaders
  • B cells: humoral immunity: production and distribution of antibodies
  • NK cells: immune surveillance: the detection and subsequent destruction of abnormal tissue cells
• life span: days to years

Question 19

What is differential blood count?

Answer 19

• RBCs outnumber WBCs 1000:1
• differential count: the number of each type of cell in a sample of 100 WBCs
• changes in infections, inflammation, and allergic reactions

Question 20

What are platelets and their other name?

Answer 20

thrombocytes
- description
- cell fragments; not complete cells. Megakaryocyte sheds cytoplasm to produce ~4000 platelets in a life time
- cytoplasm contains very small pink staining granules which contain some of the clotting factors
- function
1. release important clotting chemicals
2. temporarily patch damaged vessel walls
3. actively contract tissue after clot formation
- life span: 7 - 12 days

Question 21

What is the organization of the immune system?

Answer 21

• nonspecific immunity
  
  • do not distinguish one type of threat from another
• specific immunity
  
  • protect against particular threats
• both nonspecific and specific immune responses are complementary and must function normally

Question 22

What is the physical barrier do?

Answer 22

• keep hazardous materials outside the body by
  
  • epithelial covering barrier
  • specialized accessory structures and secretions of epithelial cells
    
    • hair
    • secretions (sweat, mucus, urine, etc.)
      
      • flush surface
      • contain bactericidal chemicals: lysozyme, antibodies

Question 23

What do phagocytes do?

Answer 23

• first line of cellular defense
  
  • microphages: neutrophils and eosinophils
  • macrophages: fixed macrophages and free macrophages
• attack and remove dangerous microorganisms
  
  • engulf a pathogen
  • bind to or remove a pathogen with assistance by other cells
  • destroy its target by releasing toxic chemicals

Question 24

What is immunological surveillance?

Answer 24

• natural killer (NK) cells recognize and destroy abnormal cells by detecting the antigens on the cell membrane of abnormal cells

Question 25

What are interferons?

Answer 25

• small proteins released by activated lymphocytes and macrophages and by tissue cells infected with viruses
• functions
  
  • trigger productions of antiviral proteins in normal cells
  • antiviral proteins
    
    • do not kill viruses
    • block replication in cell

Question 26

What is the complement system?

Answer 26

• 11 complement proteins (C)
• complements, or supplements the action of antibodies
• functions
  
  • destruction of target cell membranes by forming the membrane attack complex (MAC) which creates a pore for cell lysis

Question 27

What is inflammation?

Answer 27

• the first step in the healing process, characterized by swelling, redness, warmth, pain, and some loss of function
• histamine: increases capillary permeability; heparin: inhibits clotting
• function:
  
  1. temporary repair and barrier against pathogens
  2. retards spread of pathogens into surrounding areas
  3. mobilization of local and systemic defenses

Question 28

What does a fever do?

Answer 28

• pyrogens
  
  • proteins that can reset body’s thermostat and raise body temperature
  • pathogens, bacterial toxins, and antigen-antibody complexes
• within limits, for each 1 C rise in temperature, metabolism rate jumps by 10%

Question 29

What are specific defenses?

Answer 29

• specific resistance (immunity)
  
  • responds to specific antigens
  • with coordination action of T cells and B cells

Question 30

What are T-cells?

Answer 30

• thymus-dependent, 80% of circulating lymphocytes
• 3 main types:
  
  • cytotoxic T cells (killer T cells)
    
    • attack cells physically by releasing perforin
    • produce cell-mediated immunity
  • Helper T cells
    
    • secrete cytokines to stimulate both T cells and B cells
    • most numerous T cells
  • suppressor T cells
    
    • inhibit T cell and B cell activities

Question 31

What is cell mediated immunity?

Answer 31

involves close physical contact between activated killer T cells and foreign, abnormal or infected cells

Question 32

What are B cells?

Answer 32

• responsible for antibody-mediated immunity
• attack antigens by producing specific antibodies
• millions of populations, each with different antibody molecules

Question 33

What is the structure of an antibody?

Answer 33

• 2 parallel pairs of polypeptide chains
  
  • 1 pair of heavy chains
  • 1 pair of light chains
• each chain contains
  
  • constant segments
    
    • 5 types: IgG, IgE, IgD, IgM, or IgA
  • variable segments
    
    • contains antigen binding sites
    • determines the specificity of the antibody
    • ~ 100 million types of antibodies

Question 34

What is an IgG antibody?

Answer 34

• 80% of all antibodies
• mainly in plasma

Question 35

What is an IgE antibody?

Answer 35

• attaches to exposed surfaces of basophils and mast cells
• important in allergic response

Question 36

What is an IgD antibody?

Answer 36

• on surface of B cells
• involved in B cell activation

Question 37

What is an IgM antibody?

Answer 37

• first classes of antibody secreted after an antigen arrives
• effective in forming immune complexes

Question 38

What is an IgA antibody?

Answer 38

primarily in glandular secretions: mucus, tears, saliva

Question 39

What is the 7 actions of antibodies?

Answer 39

1. neutralization of antigen binding sites
2. precipitation and agglutination
   
   1. formation of immune complex
3. activation of complement
4. attraction of phagocytes
5. opsonization
   
   1. increasing phagocyte efficiency
6. stimulation of inflammation
7. prevention of bacterial and viral adhesion